NAME
getpass —
get a password
SYNOPSIS
#include <pwd.h>
#include <unistd.h>
char *
getpass(const
char *prompt);
DESCRIPTION
The
getpass()
function displays a prompt to, and reads in a password from,
/dev/tty. If this file is not accessible,
getpass() displays the prompt on the standard error
output and reads from the standard input.
The password may be up to _PASSWORD_LEN
(currently 128, as defined in the
<pwd.h> include file)
characters in length. Any additional characters and the terminating newline
character are discarded.
getpass()
turns off character echoing while reading the password.
The calling process should zero the password with explicit_bzero(3) as soon as possible to avoid leaving the cleartext password visible in the process's address space.
RETURN VALUES
Upon successful completion, getpass()
returns a pointer to a NUL-terminated string of at most
_PASSWORD_LEN characters. If an error is
encountered, the terminal state is restored and a null pointer is
returned.
FILES
- /dev/tty
ERRORS
- [
EINTR] - The
getpass() function was interrupted by a signal. - [
EIO] - The process is a member of a background process attempting to read from its controlling terminal, the process is ignoring or blocking the SIGTTIN signal or the process group is orphaned.
- [
EMFILE] - The process has already reached its limit for open file descriptors.
- [
ENFILE] - The system file table is full.
SEE ALSO
STANDARDS
Historically, BSD versions of
getpass() have accepted a password on the standard
input if /dev/tty is unavailable. This contradicts
X/Open Portability Guide Issue 4, Version 2
(“XPG4.2”) but the OpenBSD
implementation is conformant in all other respects. Removed from
IEEE Std 1003.1-2001 (“POSIX.1”).
HISTORY
A getpass() function appeared in
Version 7 AT&T UNIX.
CAVEATS
The getpass() function leaves its result
in an internal static object and returns a pointer to that object.
Subsequent calls to getpass() will modify the same
object.